Add version arg to main.css to bust caches

Author: Bjwebb

prefix_finder/frontend/templates/base.html

@@ -17,7 +17,7 @@
 
     <!-- Styles -->
     <link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons">
-    <link rel="stylesheet" href="{% static 'css/main.css'%}">
+    <link rel="stylesheet" href="{% static 'css/main.css'%}?version=2">
     {% block extra_style %}{% endblock %}
     {% get_favicons prefix="favicons/" %}
   </head>